From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Sent: Friday, March 6, 2020 7:27 AM > > Jon Doron <arilou@xxxxxxxxx> writes: > > > Add support for Hyper-V synthetic debugger (syndbg) interface. > > The syndbg interface is using MSRs to emulate a way to send/recv packets > > data. > > > > The debug transport dll (kdvm/kdnet) will identify if Hyper-V is enabled > > and if it supports the synthetic debugger interface it will attempt to > > use it, instead of trying to initialize a network adapter. > > > > I would suggest you split TLFS changes into it's own patch so Hyper-V > folks can ACK (or they can ack the whole patch with KVM changes of > course :-) I have contacted the Hyper-V team for clarification of the status of the synthetic debugging feature and the associated CPUID leaves and MSRs. The first statement I got is that these are "deprecated", but I'm trying to get more specifics about exactly what that means, if they are going to be removed in a future release. Michael > > > Signed-off-by: Jon Doron <arilou@xxxxxxxxx> > > --- > > arch/x86/include/asm/hyperv-tlfs.h | 16 ++++ > > arch/x86/include/asm/kvm_host.h | 13 ++++ > > arch/x86/kvm/hyperv.c | 114 ++++++++++++++++++++++++++++- > > arch/x86/kvm/hyperv.h | 5 ++ > > arch/x86/kvm/trace.h | 25 +++++++ > > arch/x86/kvm/x86.c | 9 +++ > > include/uapi/linux/kvm.h | 10 +++ > > 7 files changed, 191 insertions(+), 1 deletion(-) > > > > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h > > index 92abc1e42bfc..8efdf974c23f 100644 > > --- a/arch/x86/include/asm/hyperv-tlfs.h > > +++ b/arch/x86/include/asm/hyperv-tlfs.h > > @@ -33,6 +33,9 @@ > > #define HYPERV_CPUID_ENLIGHTMENT_INFO 0x40000004 > > #define HYPERV_CPUID_IMPLEMENT_LIMITS 0x40000005 > > #define HYPERV_CPUID_NESTED_FEATURES 0x4000000A > > +#define HYPERV_CPUID_SYNDBG_VENDOR_AND_MAX_FUNCTIONS 0x40000080 > > +#define HYPERV_CPUID_SYNDBG_INTERFACE 0x40000081 > > +#define HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES 0x40000082 > > > > #define HYPERV_HYPERVISOR_PRESENT_BIT 0x80000000 > > #define HYPERV_CPUID_MIN 0x40000005 > > @@ -131,6 +134,8 @@ > > #define HV_FEATURE_FREQUENCY_MSRS_AVAILABLE BIT(8) > > /* Crash MSR available */ > > #define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE BIT(10) > > +/* Support for debug MSRs available */ > > +#define HV_FEATURE_DEBUG_MSRS_AVAILABLE BIT(11) > > /* stimer Direct Mode is available */ > > #define HV_STIMER_DIRECT_MODE_AVAILABLE BIT(19) > > > > @@ -194,6 +199,9 @@ > > #define HV_X64_NESTED_GUEST_MAPPING_FLUSH BIT(18) > > #define HV_X64_NESTED_MSR_BITMAP BIT(19) > > > > +/* Hyper-V synthetic debugger platform capabilities */ > > +#define HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING BIT(1) > > + > > hyperv-tlfs.h is not perfectly structured but still there is some > structure there, > e.g. HV_X64_NESTED_GUEST_MAPPING_FLUSH/HV_X64_NESTED_MSR_BITMAP/... are > said to be HYPERV_CPUID_ENLIGHTMENT_INFO.EAX > bits (see above HV_X64_AS_SWITCH_RECOMMENDED). > > To make it clear that HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING doesn't > belong to these bits I'd suggest you add a comment like > > /* > * Hyper-V synthetic debugger platform capabilities. > * These are HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES.EAX bits. > * > */ > > to make it clear. > > > /* Hyper-V specific model specific registers (MSRs) */ > > > > /* MSR used to identify the guest OS. */ > > @@ -267,6 +275,14 @@ > > /* Hyper-V guest idle MSR */ > > #define HV_X64_MSR_GUEST_IDLE 0x400000F0 > > > > +/* Hyper-V Synthetic debug options MSR */ > > +#define HV_X64_MSR_SYNDBG_CONTROL 0x400000F1 > > +#define HV_X64_MSR_SYNDBG_STATUS 0x400000F2 > > +#define HV_X64_MSR_SYNDBG_SEND_BUFFER 0x400000F3 > > +#define HV_X64_MSR_SYNDBG_RECV_BUFFER 0x400000F4 > > +#define HV_X64_MSR_SYNDBG_PENDING_BUFFER 0x400000F5 > > +#define HV_X64_MSR_SYNDBG_OPTIONS 0x400000FF > > + > > /* Hyper-V guest crash notification MSR's */ > > #define HV_X64_MSR_CRASH_P0 0x40000100 > > #define HV_X64_MSR_CRASH_P1 0x40000101
